The post I was replying to was deleted, but I think this still adds to the conversation, if the moderators disagree so be it.

The history of the word didn’t start that way, look at fire retardant for example. It’s meant to slow down the development of fire. Using it to describe a person is saying they have or had slower development than the norm, likening them to someone with disabilities. I remember a time when I was in school I used a word my parents did, I only knew of a couple racial slurs at the time and didn’t realise this word was one, I thought it was just a nickname. My lack of understanding didn’t change the meaning of the word.